1. Technical Field
The inventive concept relates to a distributed antenna system (DAS), and more particularly, to a passive intermodulation (PIM) measurement device for measuring a PIM in a distribution network or/and installation equipments within a DAS, and a relay unit including the PIM measurement device.
2. Background Art
Passive intermodulation (PIM) is a spurious signal generated by nonlinear characteristics of a passive element, and refers to a phenomenon in which the signal-to-noise characteristic is deteriorated on a communication path, thereby degrading communication quality. PIM characteristics in equipments of a distributed antenna system (DAS) are maintained to have a predetermined quality or more in production of the equipments, but a problem of PIM may occur in a field due to a passive element used in a distribution network from the rear end of an antenna port of a remote unit to a final antenna. In a conventional DAS, when a problem of PIM problem occurs in the field, it is very difficult to detect an exact occurrence position, a cause and the like of the PIM. Therefore, it is necessary to develop a plan for enabling a PIM to be measured in a DAS.